SearchEngineLand’s Danny Sullivan detailed today how Yahoo is not doing so hot with its Microsoft search deal and may soon go searching—no pun intended— for a new partner (a.k.a. Google) if performance doesn’t get better.

Yahoo’s new CEO, Marissa Mayer, a former top-tier Google Search exec, could encourage a partnership between the two polar search engines. On the other hand, Mayer brings a completely new level of knowledge to the fledging Yahoo due to her 13 years in Search with Google, so she could just help Yahoo to revamp Search with improved monetization.

Sullivan predicts some “hard renegotiating between Yahoo and Microsoft, with Google used as a cattle prod for Yahoo to shock Microsoft with.” Of course, we will have to wait and see whether Microsoft delivers on its search promises or if Yahoo will jump ship and snag a Google Search alliance—with Mayer leading the charge.

Of course, Yahoo can’t walk away [from Microsoft] without finding another partner, and it has a real shortage of choices. There’s no one left in the US with the proven ability to deliver search queries at the volume Yahoo would demand.

Ask.com? It’s largely outsourced to Google these days. Blekko? I’m sure it would love the job, but there would be a huge scaling-up challenge and, I’d say, much more work to do on the relevancy front. Maybe Yandex or Baidu could make a bid?

It won’t be Yahoo. Yahoo has lost too much key search talent and hasn’t kept its core search technology up-to-date. When it gave itself over to Microsoft, Yahoo really left itself without a “Plan B.”

My post from earlier this week, Ironically, Search Might Be Less A Priority At Yahoo As Google’s Marissa Mayer Takes The Helm, gets into these issues more — as well as the one realistic alternative to Microsoft. Google.